Oral alkali production and caries prevention in children

摘要 这是一个修改后的K23奖博士Marcelle Nascimento，助理教授在 佛罗里达大学牙科学院。纳希门托医生一直在进行临床翻译 研究项目侧重于口腔细菌定植的产碱能力及其在 口腔健康和龋齿。Nascimento博士的目标是成为一个领先的和独立的研究人员在 该领域的Cariology和追求创造新的治疗目标的基础上口服碱生产， 可能会从根本上改变我们评估龋齿风险和预防龋齿的方式。她已经组装了一个 由Robert Burne博士（UFCD）、Robert Primosch博士（UFCD）和弗洛伊德博士组成的杰出指导小组 Dewhirst（福赛斯研究所）和顾问Jorge Frias-Lopez博士（福赛斯研究所）确保成功 她的职业发展和拟议的研究学习。这个K23奖项将大大促进她的职业生涯 通过提供结构和获得指导来发展：（1）设计和 开展面向患者的研究，（2）生物信息学和微生物组数据分析培训，（3） 在申请和管理联邦资金方面的经验和指导，以及（4）时间释放和 在奖励期结束前生成数据和出版物以支持RO 1申请的资源。 口腔细菌产生的碱对牙菌斑生物化学和代谢有重大影响， 降低口腔生物膜的致龋性的方式。虽然已知菌斑细菌的酸产生 作为龋齿的直接原因，值得注意的是， 发生在牺牲的物种，是较低的耐酸和通常与口腔健康-许多 它们被认为是产碱细菌。生物膜中产碱细菌的损失 人群可能会降低牙菌斑中和酸的能力，并减缓牙菌斑pH值的恢复， 中立的价值观Nascimento博士的研究小组的临床研究提供了重要的支持，即缺乏 口腔细菌产生的碱性物质可能是成年人龋齿风险的关键决定因素。具体而言是 来自无龋受试者的牙菌斑和唾液的细菌群体具有更大的产生 当精氨酸是口腔中主要的产碱基质之一时，来自精氨酸的氨 与来自龋齿活跃受试者的细菌群体相比。微生物组成的差异， 产碱系统的调节可能是影响口腔样本容量的关键因素， 不同的受试者代谢精氨酸。在已知的口腔细菌的产碱系统中，精氨酸是最常见的。 脱亚胺酶系统（ADS）可能是斑块中唯一最重要的pH稳态机制， 似乎主要有助于抵抗龋齿。通过精氨酸脱羧酶 (ADC)精氨酸也可被胍丁胺脱亚胺酶分解代谢为胍丁胺， AgDS系统。虽然她最近在口服溶栓剂活性方面有了新的重要发现， 成人临床研究和儿童初步研究，口腔细菌的精氨酸分解代谢潜力 从不同龋齿状态的儿童仍然没有探索，尽管这一途径的重要性， 菌斑pH稳态和龋齿。同样，关于口腔细菌的基本问题仍然存在： (a)体质性溶血能力，（B）对ADS和AgDS调节的敏感性，（c）体质性酸 抗性，和（d）基因含量，因为它与ADS和AgDS在口腔生物膜生态学中的作用相关， 健康和疾病。因此，拟议实验的目标是：（一）继续调查 精氨酸和胍丁胺的口服产碱与儿童患龋经验之间的关系， 及（ii）深入了解龈上组织的基本微生物学、生态学和宏基因组学 产氨细菌群落及其与口腔健康和龋齿的关系。这些 研究将为制定新的龋齿风险策略提供必要的基线信息 评估和龋齿控制，其基于通过碱改变口腔生物膜pH和生态 生产

ABSTRACT This is a revised application for the K23 award for Dr. Marcelle Nascimento, an Assistant Professor at the University of Florida, College of Dentistry (UFCD). Dr. Nascimento has been conducting clinical-translational research projects focusing on the alkali-producing capacity of bacteria colonizing the oral cavity and its role in oral health and dental caries. Dr. Nascimento aims to become a leading and independent researcher in the field of Cariology and to pursue the creation of novel therapeutic targets based on oral alkali production that may fundamentally change the way in which we assess caries risk and prevent caries. She has assembled an outstanding mentoring group comprised by Drs. Robert Burne (UFCD), Robert Primosch (UFCD) and Floyd Dewhirst (Forsyth Institute) and the consultant Dr. Jorge Frias-Lopez (Forsyth Institute) to insure the success of her career development and proposed research study. This K23 award will greatly facilitate her career development by providing the structure and the guidance for acquiring: (1) expertise on designing and conducting patient-oriented studies, (2) training on bioinformatics and microbiome data analysis, (3) experience and mentoring in requesting and managing federal funds, and (4) the time release and the resources to generate data and publications to support an RO1 application by the end of the award period. Alkali production by oral bacteria has a major impact on dental plaque biochemistry and metabolism in a manner that reduces the cariogenicity of oral biofilms. Although acid production by plaque bacteria is known as the direct cause of caries, it is noteworthy that increases in the proportions of aciduric organisms appear to occur at the expense of species that are less aciduric and commonly associated with oral health - many of which have been recognized as alkali-producing bacteria. Loss of alkali-producing bacteria from the biofilm populations may reduce the capacity of plaque to neutralize acids and slow the return of plaque pH to more neutral values. Clinical studies from Dr. Nascimento's research group offer significant support that a lack of alkali production by oral bacteria may be a critical determinant of caries risk in adults. Specifically, the bacterial populations from plaque and saliva of caries-free subjects have a greater capacity to produce ammonia from arginine, which is one of the predominant alkali-yielding substrates in the oral cavity, when compared to bacterial populations from caries-active subjects. Differences in the microbial composition and regulation of the alkali-producing systems may be critical factors affecting the capacity of oral samples from different subjects to metabolize arginine. Of the known alkali-generating systems by oral bacteria, the arginine deiminase system (ADS) is perhaps the single most significant pH homeostasis mechanism in plaque, and appears to contribute in major ways to resistance to caries. Through the arginine decarboxylase enzyme (ADC), arginine can also be catabolized into agmantine and then into ammonia by the agmatine deiminase system (AgDS). While novel and important findings on oral arginolytic activity have recently arisen from her clinical study with adults and preliminary study with children, the arginine catabolic potential of oral bacteria from children with different caries-status remains unexplored, in spite of the importance of this pathway to plaque pH homeostasis and caries. Likewise, fundamental questions remain with regards to the oral bacteria: (a) constitutional arginolytic capacity, (b) sensitivity to regulation of the ADS and AgDS, (c) constitutional acid resistance, and (d) gene content, as it correlates to the role of ADS and AgDS in the ecology of oral biofilms, health and disease. Accordingly, the goals of the proposed experimentation are: (i) to continue to investigate the relationship between oral alkali production from arginine and agmatine and caries experience in children, and (ii) to gain insights into the fundamental microbiology, ecology and metagenomics of supragingival ammonia-producing bacterial communities and their relationship to oral health and dental caries. These studies will provide essential baseline information for the development of new strategies for caries risk assessment and caries control that are based on modification of oral biofilm pH and ecology through alkali production.